The weight of an occupant of a bed exerts tension in a longitudinal direction upon that portion of a fitted bed sheet or mattress cover engaging the ends of the bed. The ends of existing fitted bed sheets, usually at one of the corners, tend to ride up and eventually slide right off the ends of the mattress.
Attempts have been made to address this problem by having mattress cover or fitted bed sheets designs which permit material to be placed under the mattress. These designs have reduced the problem but have not been effective in eliminating it. The weakness of the existing designs become apparent when one attempts to increase the amount of material underlying the end of the mattress. In some designs the material at the ends must equal the material at the sides, this makes it difficult to place the mattress cover or fitted sheet on the mattress when the material at the ends is increased. In other designs the ends become exceedingly loose as the amount of material at the ends is increased; the designs are not functional unless an extra seam is added which limits them to one particular thickness of mattress.